Suzuki SM125: Quench the thirst

Supermotos inhabit the wild, impractical end of the motorcycling spectrum: these are hot motocross machines, often full-on competition bikes, their off-road wheels and gentle brakes replaced by sticky road rubber and powerful sports stoppers. There's no purpose except having a laugh.

Why, then, should you consider Suzuki's new DR125SM (SM125 for short) for going to work every day? One reason screams out above all others: 100mpg. Yes, one hundred miles per gallon. But you don't have to suffer for your scrimping: the SM125 might take its name and its inspiration from supermotos, but as a riding proposition it couldn't be much further from the raw, over-muscled experience delivered by the real thing.

Instead, this is an easy, forgiving machine, aimed primarily at novices, which offers the well balanced, decent quality ride that is typical of Japanese products, but which happens to be styled like a supermoto. In fact, the distinguishing features of a supermoto broaden this bike's appeal and utility rather than interfere with it. The road wheels and brakes mean the SM125 steers quickly but predictably, losing the pendulous effect that comes with large diameter off-road wheels, while the single front disc rewards with good, progressive but unintimidating power. The rear brake is a fashionable disc, too, although the bike would fare better with a dull old drum at the back as these provide much better feel - there's little feedback until suddenly the wheel is locked.

The upright riding position and fairly wide bars are ideal for dodging urban traffic, enhancing your vision and the bike's manoeuvrability and, crucially in this class, that also means the bike suits taller people - many 125s seem designed for smaller riders, as if a bike's capacity should reflect its rider's stature.

The air-cooled engine dates back to the mid-1980s when it powered a basic Suzuki 125, the GS, and not a lot has changed since then apart from the important addition of an elegantly simple fuel-injection system. Usually the expense and packaging problems associated with fuel injection are why small capacity machines have carburettors, but the SM's Mikuni-developed discharge pump injection does away with the high-pressure pump, fuel lines and high electrical demands of conventional systems. Instead there's a single component comprising a solenoid with a plunger to squirt fuel directly into the inlet tract, the amount it injects determined by the number of times it operates, which can be hundreds of times for each engine revolution.

The result is impressive, partly because the engine feels responsive and happy to rev, but mainly, in the current climate (economic and environmental) because it uses fuel so sparingly. I rode the bike for 50 miles in a range of circumstances, across three busy town centres, along country lanes and with nearly half the mileage spent on fast A-roads (much of that dual carriageway). And I was riding it normally, which meant throttle against the stop for mile after mile on the A-roads to maintain its flat-out 60-65mph top speed, revving it heartily at the front of traffic queues to make sure I got away cleanly, and spinning the engine close to its red line. Fifty-four miles later the two-gallon fuel tank took only 2.46 litres to brim which, in units that mean something, was 0.54 gallons: 100mpg.

You could certainly improve on that by taking it easy, but anything less than flat-out on A-roads could be dangerously slow: as it is, you're dicing with big trucks limited to the same top speed. Even so, a relaxed rider is likely to achieve a Chancellor-cheating 120mpg. So compare that with your resource-hungry Toyota Prius… The power unit's age is betrayed by a rather notchy gearchange, while the engine idle wasn't entirely reliable, the motor stopping for no particular reason now and then. This happened on more than one machine so it wasn't an isolated fault, although it fired up easily again after a touch of the starter button. You also get a lot of piston noise, a rumble that's amplified by the cooling fins.

All of which pales against the money (and planet) you'd save by buying one of these as a commuting saviour. Comfort is fine for a couple of hours, it'll be reliable and cheap to service, it's easy to ride for novices and surprisingly rewarding for the experienced. And, towering over every other consideration, there's its 100mpg economy.